U.S. Pat. No. 4,193,875, commonly assigned with the present case, the literature cited therein and pages 270ff. of Filtration and Separation, May/June 1974, describe modern multi-disk rotary filters in which a horizontal shaft is rotatable relative to a housing or trough into which a slurry or suspension to be filtered can be fed, the shaft carrying a plurality of axially spaced filter disks lying in respective vertical planes and subdivided into a multiplicity of filter sections or cells which successively are immersed in the suspension in the trough and from which filtrate can be evacuated or withdrawn to allow filter cakes to collect on the filter cloth or other filtering surface of the disk.
The filter cakes may be washed, drained from liquid and dislodged by evacuation of fluid from or the supply of fluid to the respective filter cells via fluid passages communicating between these cells and a distributing head or control or valving member at an end of the shaft.
The filter disks each comprise a cell carrier which may be fixed to the hollow shaft and which can be formed with a plurality of angularly equispaced radial openings, each communicating with a respective filter cell and with which the aforementioned passages communicate in turn.
In the aforementioned patent, the passages are disposed outwardly of the shaft and are fixed thereto while having axially extending sections parallel to the shaft axis and or curved sections which run into radial sections or open radially in the filter cell carriers.
When the filter is used continuously for long periods in corrosive or abrasive media, the passage-forming members must be replaced from time to time. While the arrangement disclosed in the aforementioned patent represents a vast improvement over earlier systems, nevertheless the replacement of the passage-forming members has frequently necessitated replacement of the filter cell carriers as well, a complex and time-consuming procedure which requires a comparatively long interruption in the operation of the filter.